Cursor positioning device operable over various degrees of elevation

ABSTRACT

The present invention relates to cursor control devices for computers, and particularly relates to cursor control devices for personal computers which involve the use of a ball rotatable by the fingers for controlling cursor movement.

BACKGROUND OF THE INVENTION

.Iadd.This is a reissue of U.S. Pat. No. 5,008,528. .Iaddend.

With the burgeoning use of the personal computer and computerworkstation, it has become increasingly important to the users of suchcomputer to have convenient control of the cursor on the computer'svideo display.

The simplest form of cursor control for such computers involves the useof cursor keys, typically located on the keyboard for the computer.However, use of the cursor keys tends to give only very slow and awkwardperformance. An alternative to the cursor keys is the light pen, whichuses a light beam on a special reflective surface to move the cursor.

A more recently developed cursor control device is the electronic mouse.Electronic mouse come in two general types. The first type usersreflection of a light beam off a coded surface to control cursormovement. The more versatile, and more popular, mouse, such as theLogitech C7 mouse manufactured by the assignee of the present invention,provides optomechanical operation which requires nothing more than aflat surface over which the mouse can be rolled. Such electronic micecomprise a case held in the hand. In the bottom of the case is africtional ball. Cursor movement is controlled by holding the case inthe hand such that the ball engages the flat surface. The ball alsofrictionally engages shaft encoders which convert the analog movement ofthe ball into digital cursor control. One of the limitations ofelectronic mice, however, is that they have needed a flat surface of atleast several square inches to be used. Such surface area is not alwaysavailable, and so an electronic mouse is not a solution in allsituations.

Another cursor control device is the trackball. Trackballs, whichsimilar to electronic mice, differ in some very significant respect.While mice typically have cases formed to be held in the hand, and thushave relatively small rolling balls, trackballs are designed to have thecase remain stationary, with only the ball being rotated. Thus, the ballis markedly larger than for an electronic mouse. In addition, the ballfor a mouse must smoothly engage the surface over which it rolls, andthus is typically coated with rubber or similar polymer, and is weightedto ensure good frictional engagement. A trackball, on the other hand, iscontrolled by direct contact with the hand, and thus needs no suchcoating since finger pressure can be varied to ensure frictionalengagement.

One of the difficulties with trackballs in the past has been that thecases of such trackballs were large, to accommodate the large ballneeded for convenient hand movement. In addition, conventionaltrackballs typically have been intended for use within only a verynarrow range of elevational angles, and could not be used in, forexample, the inverted position. As the result of these and otherlimitations, the trackball has been primarily intended as a stationarycursor control device.

There has therefore been a need for a cursor control device which can beused in very limited space, and yet still be capable of reliableoperation over a wide range of elevational angles, such as might beencountered in using a laptop computer.

SUMMARY OF THE INVENTION

The aforementioned limitations of the prior art are substantiallyovercome by the present invention, which provides a trackball devicecapable of use over a wide range of elevational angles which requiringonly very nominal surface area for mounting. In addition, the trackballof the present invention may be configured either to be fixedly mountedto a keyboard, or to be free standing.

In accordance with the present invention, a polymeric ball of a sizesuitable for manipulation by the fingers or thumb is rotatablysandwiched between a lower housing and an upper retaining ring. Flangeson the upper retaining ring rotationally engage an upper housing, topermit easy removal of the ball from the trackball device.

Rotational movement of the ball is converted to cursor movement throughengagement of the ball with optical encoders. The optical encoders mayinclude a mask for improved resolution. The relatively close engagementof the upper retaining ring and lower housing maintain the ball incontinuous frictional engagement with the encoders regardless ofelevational angle, so that the cursor may be reliably controlled withthe trackball device in any position, including inverted.

To facilitate construction and improve reliability, the opto-mechanicalencoders of the present invention reside on a modular skeleton which maybe removed as a single unit. In addition, the opto-mechanical encodersare urged into engagement with the ball by a simplified but reliablespring arrangement, which reduces manufacturing cost while improvingmanufacturability.

It is therefore one object of the present invention to provide animproved trackball device.

It is another object of the present invention to provide a trackballdevice which reliably controls cursor movement at any elevational angle.

Another object of the present invention is to provide a trackball devicewhich can be fixedly mounted to a keyboard.

Still another object of the present invention is to provide a trackballhaving improved resolution.

Yet another object of the present invention is to provide a trackballhaving improved ease of construction while at the same time havingimproved reliability.

These and other features of the present invention will be betterappreciated from the appended

FIGURES

in which

FIG. 1a is a perspective view of a trackball device in accordance withthe present invention;

FIG. 1b is an exploded perspective view of the trackball device of FIG.1a;

FIG. 1c is a side elevational view of the trackball device of FIG. 1a;

FIG. 1d is a perspective view of the underside of the upper housing ofan exemplary trackball device in accordance with the present invention;

FIG. 2a is a plan view of an assembled skeleton for a trackball devicein accordance with the present invention;

FIGS. 2b and 2c are perspective and plan views of an optomechanicalencoder in accordance with the present invention;

FIG. 2d is an elevational view of a mask for use with the encoders ofthe present invention; and

FIG. 2e is a plan view of an optical encoder in accordance with thepresent invention with the mask of FIG. 2d mounted thereon.

.Iadd.FIGS. 3A and 3B show a perspective view of a laptop computerhaving a cursor positioning device of one embodiment of the presentinvention.

FIG. 4 shows a perspective view of a computer system having a cursorpositioning device of one embodiment of the present invention. .Iaddend.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to FIG. 1a, the trackball device 10 of the presentinvention may be appreciated from its perspective view. Referring alsoto FIG. 1b, the trackball device 10 can be seen to include a skeleton20, sandwiched between a printed circuit board assembly 30 whicheffectively serves as a lower housing, a mounting bracket 40, and anupper housing 50. A ball 60 fits into a hole in the upper housing 50 andrests against a plurality of pressure rollers maintained on the skeleton20. The ball 60 may be constructed of one hundred percent polyester, orcast phenolic, or other suitable material.

The ball 60 is held in place against the pressure rollers, described ingreater detail hereinafter, by a retaining ring 70 which has flanges onits underside matched for engagement with the opening in the upperhousing 50. A plurality of screws 80 or other suitable fastenersmaintain relative positions of the upper housing 50, mounting bracket40, skeleton 20 and printed circuit board assembly 30. In the embodimentshown, the screws 80 engage posts 90 shown on the underside of the upperhousing in FIG. 1d. The assembled trackball can be appreciated from FIG.1c, where the trackball is shown in a side elevational view.

A single function selection bar 100, for causing the operation of aselected function, is shown in FIGS. 1a-d, although those skilled in theart will appreciate that a plurality of function select bars may beprovided without departing from the present invention.

Referring next to FIG. 2a, the skeleton 20 of the trackball 20 is shownin plan view. Mounted on the skeleton are all of the mechanical elementsof a pair of optomechanical encoders, referred to generally at 200 and202. The mechanical elements of each encoder include a shaft 204 mountedwithin a positioner 206 and an engagement wheel 208. Mounted on theshaft is an encoding wheel 210, which has slits in it for the selectivepassage of light.

The shaft 204 passes through a mask 212, better seen in oversized viewin FIG. 2d, which permits the mask to be juxtaposed next to the encodingwheel 210. The mask 212 may be seen to include slits, opposed at 111 orother suitable angle. A post on the mask 212 engages a receiver 213 onthe skeleton 20, which serves to position rotatably one end of the shaft204. The other end of the shaft 204, bearing the engagement wheel 208,is retained within a slotted receiver 214 (another of which also limitsthe range of movement of the other end of the shaft 204). The engagementwheel is urged into frictional contact with the ball 60 by means ofspring 216, which extends between a positioning pin 206 on the shaft 204and an opposing positioning pin 218 on the skeleton 20. The shaft 204and associated elements may be better appreciated from FIGS. 2b and 2c,where they are shown in perspective and plan views, respectively. Theshaft assembly with the mask 212 positioned next to the encoding wheelis shown in FIG. 2e.

The encoding wheel 210 and mask 212 are positioned between a pair ofphotosources and photodetectors 220a-b and 222a-b, which are affixed tothe printed circuit board 30. The movement of the ball 60 in engagementwith the wheels 208 causes the encoding wheel 210 to rotate relative tothe fixed slits in the mask 212, so that the photodetectors 220b and222b generate a quadrature signal, which may be readily converted to adigital signal indicative of position by a manner well known in the art.

To ensure smooth rotation of the ball 60, three pressure rollers 240,242 and 244 are provided. The rollers 240-244 may be of theshaft-mounted ball bearing type, as shown in FIG. 2a, and provideimproved shock loading. The ball 60 rests on the rollers 240-244, andthus does not frictionally engage the opening 246 in the skeleton 20. Inother embodiments, however, where such shock loading is not required, itmay be desirable to eliminate the pressure rollers 240-244 and to permitdirect engagement of the ball 60 with the skeleton 20.

As noted above in connection with the photosources and photodetectors220a-b, the skeleton 20, once assembled, is located over the printedcircuit board assembly 30. The PCB 30, in addition to holding thephotosources and photodetectors also supports a connector 260 by whichthe trackball 10 may be electronically connected to a personal computeror workstation (not shown). In particular, the trackball and connectorare particularly suited to be mounted into a keyboard for a portable orlaptop computer, although the trackball of the present invention willwork equally well with any other form of computer or workstation. ThePCB 30 may also hold a suitable processor or other electronics tomanipulate the quadrature signals generated by the photodetectors 220band 222b. A suitable sensing circuit is disclosed in a co-pendingapplication, Ser. No. 07/357,653, assigned to the same assignee as thepresent application.

As discussed previously in connection with FIG. 1, the mounting bracket40 cooperates with the PCB assembly 30 to permit the trackball device 10to be mounted to a selected keyboard or other receiving unit. Inaddition, it can be appreciated that the skeleton 20 and mountingbracket 40 are sandwiched between the PCB assembly 30 and the upperhousing 50, all of which are fastened together by the screws 80 (FIG.1b). The screws 80 may be seen to extend through holes 250 in theskeleton 20, as well as holes 252 in the mounting bracket 40.

The ball 60 is then retained within the trackball by the retaining ring70. The retaining ring 70, which has flanges on its underside, isrotatably locked into place in the opening 270 of the upper housing 50.The inner surface 280 of the retaining ring 70 is beveled to permit easyrotation of the ball 60. The distance between the inside of theretaining ring 70 and the pressure rollers 240-244 is sized to preciselyaccommodate the ball 60 so that the engagement of the ball 60 with theengagement wheels 208 will be maintained regardless of the elevationangle of the trackball device 10.

It can therefore be appreciated that an improved trackball device hasbeen disclosed, in which virtually all of the moving parts are mountedon a single removable sub-assembly. In this manner, a simple, reliable,easy to manufacture device is created. It can further be appreciatedthat the use of a mask provides improved resolution, while thecooperation of the lock ring, upper housing, ball and pressure rollerspermits operation of the present invention at any elevational angle.

Having fully disclosed one embodiment of the invention, it will beappreciated by those skilled in the art, given the teachings herein,that numerous alternatives and equivalents exist which do not departfrom the present invention. It is therefore to be understood that thepresent invention is not to be limited by the foregoing description, butonly by the appended claims.

What is claimed is:
 1. A trackball comprisinga lower housing member, aball suitable for rotational manipulation by the fingers and generallyaccessible through the upper surface of the trackball, a skeleton memberhaving ball receiving means therein for receiving the ball, a pluralityof optomechanical encoders having the mechanical components thereofmounted on the skeleton member and urged into mechanical engagement withthe ball, the mechanical components supporting the ball, an upperhousing member having ball retaining means and capable of being fixedlymounted to the lower housing member and thereby fixedly locating atleast the skeleton member therebetween.
 2. The trackball of claim 1wherein the skeleton member further includes pressure roller means forrotatably supporting the ball.
 3. The trackball of claim 1 wherein theencoders are urged into mechanical engagement with the ball by coilsprings.
 4. The trackball of claim 1 wherein the optomechanical encodersinclude a mask and an encoding wheel for generating quadrature signals.5. The trackball of claim 1 wherein the ball retaining means of theupper member cooperates with the ball receiving means of the skeletonmember to maintain the ball in contact with the optomechanical encodersat all elevational angles.
 6. A trackball comprisinga ball suitable forrotational manipulation by the fingers and generally accessible throughthe upper surface of the trackball, a lower member having mountedthereon a plurality of photosources and photodetectors, a skeletonmember having mounted thereon a plurality of shafts, each shaft havingmounted thereon an optical encoding wheel and a ball engagement wheel,each optical encoding wheel being disposed to be located between thephotosource and the photodetector, the plurality of shafts providing atleast partial support for the ball, an upper housing adapted to befixedly mounted to the lower member and for fixedly locatingtherebetween the skeleton member, the uppoer housing having therein anopening for passing the ball therethrough, and ball retaining meanscapable of being fixedly mounted to the upper housing for maintainingthe ball in contact with the ball engagement wheels regardless ofelevational angles.
 7. The trackball of claim 6 wherein the lower memberincludes printed circuit means. .Iadd.
 8. A cursor control devicecomprising:a lower housing member; a ball suitable for rotation throughan opening defined by said lower housing member; a skeleton memberhaving ball receiving means therein for receiving the ball; a pluralityof encoders having mechanical components thereof mounted on saidskeleton member, said mechanical components engaged with said ball fordetecting rotational motion of said ball; an upper housing member havingball retaining means and capable of being fixedly mounted to the lowerhousing member and thereby fixedly locating at least the skeleton membertherebetween, wherein a centerpoint of said ball remains equidistantfrom said lower housing member when said cursor control device isinverted. .Iaddend. .Iadd.
 9. The cursor control device as recited inclaim 8 wherein said mechanical components are urged into mechanicalengagement with said ball by an urging means. .Iaddend. .Iadd.10. Thecursor control device as recited in claim 9 wherein said urging means isa spring. .Iaddend. .Iadd.11. The cursor control device as recited inclaim 10 wherein said skeleton member further includes pressure rollermeans for rotatably supporting said ball. .Iaddend. .Iadd.12. The cursorcontrol device as recited in claim 11 wherein said plurality of encodersare optomechanical encoders. .Iaddend. .Iadd.13. A cursor control devicefor entering commands into a computer, comprising:a housing; a rotatableball within said housing; a first ball retainer in contact with saidball at a point on a first side of a centerline of said ball, said firstball retainer including a plurality of encoding means contacting saidball for generating an electrical signal corresponding to rotationalmovement of said ball; and a second ball retainer positioned for contactwith said ball at a point on a second side of said centerline of saidball and holding said ball in contact with said encoding meansregardless of the elevational orientation of said housing. .Iaddend..Iadd.14. The cursor control device as recited in claim 13 wherein saidhousing is comprised of an upper member and a lower member and saidsecond ball retainer is removably coupled to said upper member..Iaddend. .Iadd.15. The cursor control device as recited in claim 14wherein said first ball retainer is further comprised of a plurality ofpressure rollers for rotatably supporting said ball. .Iaddend. .Iadd.16.A cursor control device comprising: a ball suitable for rotationalmanipulation; a lower assembly having ball receiving means therein forreceiving and supporting said ball, said lower assembly further havingmounted thereon encoding means for detecting rotational motion of saidball and translating said rotational motion into cursor control signals;an upper housing coupled to said lower assembly, said upper housinghaving therein an opening for passing said ball therethrough; and ballretaining means coupled to said upper housing, said ball retaining meansfor maintaining said ball in contact with said encoding means regardlessof elevational angle. .Iaddend. .Iadd.17. The cursor control device asrecited in claim 16 wherein said lower assembly is comprised of askeleton member and a printed circuit assembly. .Iaddend. .Iadd.18. Thecursor control device as recited in claim 17 wherein said skeletonmember further includes pressure roller means for rotatably supportingsaid ball. .Iaddend. .Iadd.19. A keyboard for providing input to acomputer system, said keyboard comprising:a first portion having aplurality of alpha-numeric keys for providing alpha numeric input tosaid computer system; a second portion having a trackball forcontrolling a cursor on a display coupled to said computer system, saidsecond portion comprised of: a ball suitable for rotationalmanipulation; a lower assembly having ball receiving means therein forreceiving and supporting said ball, said lower assembly further havingmounted thereon encoding means for detecting rotational motion of saidball and translating said rotational motion into cursor control signals;an upper housing coupled to said lower assembly, said upper housinghaving therein an opening for passing said ball therethrough; and ballretaining means coupled to said upper housing, said ball retaining meansfor maintaining said ball in contact with said encoding means regardlessof elevational angle. .Iaddend. .Iadd.20. A computer command apparatusfor entering commands into a computer, comprising: a housing; arotatable ball within said housing; a first ball retaining member inabutting contact with said ball below a horizontal centerline of saidball; a pair of encoder shafts within said housing and in frictionalcontact with said ball such that rotation of said ball causes saidencoder shafts to rotate; a second ball retaining member positionedabove the horizontal centerline of said ball, said second ball retainingmember being adapted to retain said ball within said housing and infrictional contact with said pair of encoder shafts throughout a 360°elevational rotation of said housing; and a spring member assemblywithin said housing, said spring member assembly being positioned toretain said encoder shafts in frictional contact with said ball..Iaddend. .Iadd.21. A computer system having:a process for processinginformation; storage means for storing data; a display device fordisplaying data; and a keyboard comprising:a first key portion having aplurality of alpha-numeric keys for providing alpha numeric input tosaid computer system; a second portion having a trackball forcontrolling a cursor on said display, said second portion comprised of:a ball suitable for rotational manipulation; a lower assembly havingball receiving means therein for receiving and supporting said ball,said lower assembly further having mounted thereon encoding means fordetecting rotational motion of said ball and translating said rotationalmotion into cursor control signals; an upper housing coupled to saidlower assembly, said upper housing having therein an opening for passingsaid ball therethrough; and ball retaining means coupled to said upperhousing, said ball retaining means for maintaining said ball in contactwith said encoding means regardless of elevational angle. .Iaddend..Iadd.22. A laptop computer having: a process for processinginformation; a keyboard for input of information to said processor; anda cursor control device for producing signals to control cursormovement, said cursor control device mounted into said keyboard andbeing electrically connected to said laptop computer, said cursorcontrol device having: a ball suitable for rotational manipulation; alower assembly having all receiving means therein for receiving andsupporting said ball, said lower assembly further having mounted thereonencoding means for detecting rotational motion of said ball andtranslating said rotational motion into cursor control signals; an upperhousing coupled to said lower assembly, said upper housing havingtherein an opening for passing said ball therethrough; and ballretaining means coupled to said upper housing, said ball retaining meansfor maintaining said ball in contact with said encoding means regardlessof elevational angle. .Iaddend.